Campbell Mark Swan

There are two. They look like gardens or forests growing human body parts instead of plants, one colored silver and the other gold. Each occupies a substantial fraction of the surface of its world. The worlds' histories diverged long enough ago that they aren't recognizable as earths, and they don't seem to have native life of any kind. Cam's four-dimensional vision can also see that each entity has a tiny protrusion, humanoid and barely larger than the human average, poking into Earth Bet from the planet dominated by the body of the entity itself and, in the gold one's case, rescuing a kitten from a tree.